The invention relates to an exchangeable memory unit and a method for booting a server, particularly an aircraft server, and also to a server having an exchangeable memory unit.
When a computer has been switched on, an operating system is loaded. The starting or starting-up of the computer is also called booting. In a conventional boot operation, a processor starts at a stipulated address to execute a BIOS (Basic Input Output System) stored in a non-volatile memory. The BIOS is a firmware program which is stored in a non-volatile memory, for example in a ROM store, and which is executed immediately after the computer is switched on. The BIOS performs various functions, such as a self-test for the connected appliances (POST: Power On Self Test) or initialization of the hardware. In addition, the BIOS establishes the data storage medium from which the operating system can be booted. Next, the BIOS loads what is known as a bootloader from this data storage medium. The bootloader or the bootloader program loads the rest of the software of the operating system, with the bootloader either immediately loading the operating system stored on the relevant data medium or providing a menu for the purpose of selecting an operating system as what is known as a boot manager.
In the case of the conventional approach to booting the computer, the operating system and the bootloader program or the bootloader are located in a primary memory (primary repository), which is normally the hard disk of the computer. In this case, the BIOS program accesses the hard disk directly, with the bootloader which is on the hard disk being executed by the processor. If the computer, which may be a server, for example, is faulty, it is necessary to replace the server, including the data. If the stored data are corrupt or erroneous, it is necessary to reinitialize the computer.
If the computer is an autonomous server, for example an aircraft server, the server is reinitialized or exchanged by a maintenance team, which checks the last version and the state of the server data and if appropriate reinitializes or exchanges the server. However, both the reinitialization and the exchange of a server are usually associated with a not inconsiderable time involvement. If the server is an autonomous server in an autonomous system or in an autonomous network, this necessary maintenance time is not always available. If the server is in an aircraft, for example, a server can be reinitialized or exchanged only on the ground, for example when the aircraft is at an intermediate stop. The typical time window for such a ground stop for performing reinitialization, exchange or maintenance of the server is usually only less than 45 minutes in that case. Since a maintenance team needs to board the aircraft, perform the maintenance operation and then leave the aircraft again in this time, the effective time which is available for performing the reinitialization or possibly exchange of the server is even less. In many cases, the time-intensive maintenance operations cannot be performed in full within the given time window. Furthermore, the maintenance work on the server needs to be performed by the maintenance engineers under considerable time pressure, which means that this can result in errors. If the service engineers do not manage necessary reinitialization or exchange of an aircraft server in the available period of time, the departure time is sometimes delayed. If this results in an aircraft missing the departure time slot available to the airline, it has to wait for the next time slot for departure, which means that sometimes further delays also arise.
It is therefore an object of the present invention to provide an apparatus and a method for reliably booting an autonomous server which involve reinitialization of the server being completed within a short period of time.